The present invention generally relates to integrated circuits (IC), and more particularly to fabricating IC chips having a shelf life.
New IC technologies may include individual IC chips (i.e., “dies”) arranged into a three dimensional integrated circuit, also known as a three dimensional semiconductor package (3D package). One type of 3D package may include two or more layers of active electronic components stacked vertically and electrically joined with some combination of through substrate vias and solder bumps. Most IC chips may not have a specific shelf life. IC chips may have a long lifespan and may even last forever if not powered up.
To continue the miniaturization trend in current IC technology, copper (Cu) metallization may be extensively used due to its low resistivity and high migration resistance. However, owing to the rapid diffusion of copper into silicon (Si) and silicon dioxide (SiO2) copper structures may be covered with barrier metals and barrier insulators to prevent degradation of the IC. Copper may react with silicon at low temperatures and even at room temperature to form silicon dioxide. In the presence of oxygen, copper may act as a catalyst during the oxidation of silicon.